This application is an improvement of U.S. Pat. No. 5,931,175 (hereinafter called xe2x80x9cthe prior patentxe2x80x9d) issued to the same inventors of this application.
The prior patent disclosed an umbrella rib assembly including a top rib made of light material including aluminum alloy and an outer rib made of composite or plastic materials having good resilience and mechanical strength to be connected with the top rib. However, such a rib assembly is not suitable for forming a multiple-fold umbrella having three or two folds.
The present inventor has found the limitation of the prior patent and invented the present rib assembly provided for multiple-fold umbrella.
The object of the present invention is to provide an umbrella rib assembly including a top rib pivotally connected with a stretcher rib both being made of aluminum alloy for light weight and easy processing; a middle rib pivotally secured to the stretcher rib and a tail rib pivotally connected with the middle rib, with the middle rib and the tail rib being made of light weight carbon-fiber-reinforced plastics.